Mattress bag



FIG. 1 is a front elevation view of a mattress bag showing our new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevation view thereof; and,

FIG. 6 is a right side elevation view thereof.

The broken lines shown in the drawings are included for the purpose of illustrating portions of the mattress bag that form no part of the claimed design. 

CLAIM The ornamental design for a mattress bag, as shown and described. 